Turret control system



'- r M. A. EDWARDS ET AL ATURRET CONTROL SYSTEM Filed N63.

N m A w a Inventors. Martin A.EdWaT"dS, Kenneth K. Bowman Hi5 Attorney.

able control voltage.

Patented Aug. 22, 1944 UNITED STATES PA 'ENT OFFICE" TURRIET CONTROL SYSTEM Martin A. Edwards and Kenneth K. Bowman,-

Scotia, N. Y., assignors to General Electric Company, a corporation of New York I Application November 28, 1941, Serial No. 420,792

7 Claims.

This invention relates to control systems, more particularly to control systems for turrets and the like, and it has for an object the provision of a simple, reliable, emcient and compact control system of this character for controlling the train and elevation movement over a wide range of speed.

A more specific object of the invention is the provision of a control system of this character in which movement of a manually operated mem-.

from a separate dynamoelectric machine having a control field winding. Means responsive to one of the movements of the manually operated control member are provided for producing a vari- A potentiometer is connected across the output terminals of the supply dynamoelectric machine for one of the motors, and electrical connections are provided for applying to the control field winding the difierence I between the control voltage and the voltage drop across a predetermined portion of the potentiometer. A resistor is connected in the loop circuit between the supply dynamoelectricmachine and the armature of the drive motor and is also included in the electrical connections to the control field winding for the purpose of varying the calibration of the control in accordance with the RI drop in the armature circuit.

For a better and more complete understanding of the invention, reference should now be had to the following specification and to the accompanying drawing. in which Fig. l is a simple, diagrammatical illustration of an embodiment of the invention, and Fig. 2 is a diagrammatical sketch of an application of the invention.

Referring now to the drawing, a top-gun turret Ill of a military aircraft H is provided with a machine gun I! which it is desired to move both in train and elevation. The. machine gun I2 is provided with trunnions l3 and M which are journaled in trunnion cradles l5 and Hi to provide for elevation of the gun. The trunnion 'of conductors 2| and 22.

cradles I5 and I6 are fixedly mounted on a rotating ring H which is arranged to be rotated in azimuth by suitable driving means-illustrated as an electric motor l8. The rotating ring I'l' may be. geared to the motor 18 in any suitable manner. In the drawing the ring is illustrated as being provided with gear teeth which mesh with a pinion gear l9 which is driven bythe motor I8. l r

Current is supplied to the train motor 3 from a special armature reaction excited dynamoelectric machine 20 to the load brushes of which the armature of the motor 18 is connectedby means This armaturereaction excited machineZll is provided with an additional pair of brushes on an axis that is displaced 9|] electrical degrees from the load brushes and these additional brushes areshort circuited as indicated in the drawing. The machine 20 is provided with a'main' control field winding 203 which is arranged so that its magnetic axis coincides with the axis of the-load brushes. The flux along this axis causes a current to flow in the short circuit, and this short circuit current causes the armature to produce a flux along the 7 short circuit axis which generates" the voltage that appears across'the load-brushes of themachine. The importantcharacteristics o'fthe armature reaction excited 'dynamoelectric machine 20 are its exceptionally high speedof response,

. and its exceptionally high amplification factor, 1. e. ratio between the magnitude of the current flowing in the control winding and thecurrent flowing in the output circuit of the machine.

The dynamoelectric machine 20 is provided with compensating field windings 20b on the load axis of the machine-which neutralize the armature reaction of the machine which results from the armature current which flows in the output circuit of the machine. These compensating field windings neutralize the load armature reaction substantiallyper cent, and consequently the main control field winding 20a is only required to produce the amount of fiux necessary to cause current to flow in the short circuit. As a result, the magnitude '01 this control current is very small and this accounts for the high amplificationiactor of the machine. For the purpose of preventing surges and overshooting, the macliine 20 is provided with an antihunt field winding 20 which is arranged on the load brush axis of the machine in. such a manner as to act diflerentially with respect to p the compensating field winding 201. and it is connected. acrossthe load-brushes of themacapacitor 24.

The, ectric machine at is driven by driving means such as the directcurrent electric motor I which is supplied irom a'suitabie direct-current source such as represent d by the two conductors 2e and :1.

. A control potentiometer it is. connected across the direct-current source ".11 through the con- U tactsoi a eontactcr -Il.' Another potentiometer,

'drop reslstorril is connected in the armature circuit of dynamoelectric machine II and turret motor ll tationary contact lie of 103 I. 'is connected across the output brushes oi the supply'dynamoelectric' machine 2.. A voltage tiometer 2| is connected-to the conductor which conducts the armature current between the dynamoelectric machine It and the, motor I. and otherastationary'oontact Ilaoi the potentiometer is connected bymeans oi conductor i2 upper terminal oiv the control neld winding- 2... -The lower terminal oi the, main control'iield winding 20. is connected tothe slidercn the potentiometer ll. As a result oi these-connections; a voltageis applied to the mainfcontrol field/winding 20. 'ot dynamoelectric "which is equal tothe difleience oi yoltage the stationary con- I Qa-and Ihand the voltage across the portionjoi-themotentiometer 30 between the conductoi'gfl and slider, increased by the voltas drcp across: a resistor/II. As a result "i these jfoonnections.- the dynamoelectric machine ujisfcausedto generate a voltage which is propo cnalto the diiierence oi'the control voltage I see; ross 'the' predetermined portion oi poten- Ilgand as a iurther result, the motor II to rotate at a speed proportional to this Idiii'ereptial voltage. As previously pointed out, vonly-a current is required to excite the 1 winding 20., accordingly the voitagejacross the predetermined portion of the 30 isclosely regulated to the conoi potentiometer II and likewise,

the speed-oi'motor' II is caused to correspond closely to the control voltage oi potentiometer 2t.

. Since the voltage dropacross the resistor 3| through which the current to the turret motor is to the voltage drop acrossthe predetermined portion oi potentiometer 30, the excitation oi the control field winding. is com- :peiisatcd ,iorthe RI drop oi'the armature circuit and ass result, the speed regulation of the motor is is made independent oi the load thereon.

lication oi this apparatus is thereiore omitted ior the purpose oi simpliiying the drawing. The

potentiometer ,3. corresponds in iunction with the potentiometer 28 and produces the control voltage with respect to which the speed of the elevation-motor is is regulated.

For the purpose oi eilecting and controlling the train and elevation movements of the turret, a manually operated master controller 39 is provided. This master controller 39 may be mounted in any convenient location within the'turret.

, I 2,300,152 e a portion of a resistor 2i and a It is shown mounted on the azimuth ring gear ll.

As shown, the master controller is provided with a pistol grip which is pivotally mounted on a shaft ll. A sleeve 42 havins a wormthread is slidably mounted on the shaft in and is con-' nected by means oi an L-shaped yoke to the arm ;oi the pistol grip ll. The worm threads 0! the I sleeve ll meshwith a sector gear a which is mechanically coupled to the slider oi thepoten-v tiometer ll. Springs 42c and m; urge the sleeve to a position such that'the slider oi the poten- "tiomet'er a isin the central or item voltageposi-I" A v tion when the grip ll is.released. I

. The shaft, is iournaled in suitable bearings.

(not shown), and is connected through suitable;

gearing to one oi the input members oi a diiierential'gear 4: whose output gear is connected to the slider oi the control potentiometer II. It

' I will thus be' seen thatiithepistol grip 4. is 'moved in avertical direction, the slide! 0! the train elevation control potentiometer I! will be moved irom its central position and similarly, ii

the pistol grip 4. is moved in a horizontal direction,'the slider oi the train control potentiometer ilwiilbemoved. i r 3 A dead man" switch is is mounted in a unitabie position on the master controller II. Preierably, this dead man" switch it is mounted on the'leit-hand side oi the controller "so-that "produced hygthe potentiometer a and the voltit can'be grasped bythe leit hand while the pis-' tol grip-ll is'being grasped by the right hand. The contacts oi the "dead man" switch 44 are I preierably included in the energizing circuit for the' operating coils oi the train control contactor 2! and the corresponding contactor oi the eleva tion controller 80.

The second input element oi the diiierential gear ll is connectedthrough gearing to a ioot pedal ll which is mounted in such a position in the turret that the operator may place his ieet on the pedals when he is sitting in the normal position to operate the manual controller ll. This ioot pedal ll can be operated in a manner to supply the most oi the control ior the operation of the turret intrain, thereby leaving only a 'small percentage oi the control to be provided by operation oi the operators. master, controller 30. In other words, the master controller will be a vernier control and the pedal .operated mechanism will be the coarse control. 7 v

In order to prevent the machine gun I! from tiring into the structure oithe airplane, a contact mechanism 48 is provided in the circuit oi the tiring solenoid." This contact mechanism comprises a movable contact member ll. mounted on a lead screw a. and a cam suriaee contact member e which cooperates with the con tact member 46.. The lead, screw e is connected to one oi the trunnions oi the gunyas shown, or to some other point oi the elevation drive, and the cam member e is connected to the train drive pinion II. The contact. moves along the lead screw when the gun I! is elevated and'the cam member "c, rotates as the turret is rotated intrain. The shape oi the surface oi the cam contact e is such that it is notin contact with the contact member whenever the gun I! is in such a position that it could be fired into any part of the fuselage. As a result, when the,

gun is in such position, the circuit oi the iiring solenoid is interrupted and. the gun cannot be fired. A

With the foregoing understanding oi. the elements and theirorganization in the system, the operation of the system itseli will readily be understood from the following detailed description. The energizing circuit for the operating coil of the train control contactor 28 is completed by grasping the dead man" switch 44. This circuit is traced from the positive side oi the source 26 through the line switch 41 (in the closed position thereof), operating coil of contactor 28, and contacts of dead man" switch 44 to the opposite -side of the source. As previously pointed out a similar circuit is completed for between the voltage derived from the potentiometer 30 and the voltage or the potentiometer 28. This higher voltage is applied to the train drive motor l8 and as a result, the motor is caused to the corresponding elevation control contactor inthe controller 36. As a result. contactor 28 and" the corresponding 'contactor in controller 88 close their main contacts to apply voltages to the train control potentiometer 28 and the elevation control operate at an increased speed. Preferably, the

amount of resistance excluded from the circuit of th control field winding a is such that th speed of the motor 3 will be tripled. The upper contacts of the high speed switch 40 perform a similar function with respect to the l operation of the elevation motor 33.

Theease' and accuracy of aimingthe gun may be further increased by designing the poten-- tiometers 28 and 38 to provide a nonlinear repotentiometer 38. Contactor29 in picking up,

control voltage is applied to the stationary con-- tacts 28a and 281; which is impressed upon the control field winding 20. of dynamoelectric machine 20. As a result of this, the dynamoelectric machine 20 will generate a voltage at its load brushes which will be applied to the train drive motor l8. This voltage is also applied to potentiometer 30 and consequently the voltage between the slider of the potentiometer and the junction point of the potentiometer 38 and resistor 8| will its zero voltage position to a position in which a, Q

latlonshi'p between the 'efiective amount of the potentiometer resistance'and the position of the sliding contact. In other words, theresistance of both arms of each potentiometer is tapered from the center of each armto the endsthereoi so that the efiective amount or resistance of each arm increases nonlinearly with respect to the displacement of the contact arm. Consequently,

at relatively small displacements of the contact arm, a given increase in the displacement will produce a relatively small increase in the control voltage derived from the potentiometer. whereas at large displacements, the same increase in displacement will produce a much larger increase r in the derived control voltage.

The result of this in terms of manipulation of the gun is that when only small movements of the gun are necessary to bring it to bear on the be subtracted from the control voltage of the potentiometer 28, and the control field winding 205. will be energized by the difierence of these two voltages. A condition of balance will quickly be established with the train drive motor l8 operating at a speed proportional to the difierence 28 and the voltage derived from the potentiom of the control voltage from the potentiometer eter 30. As the gun I 2 is brought to bear on the target, the operator ceases his lateral pres sure on the pistol grip 40 and the slider of the control potentiometer 28 is returned to its central zero voltage position, with the result that the control field winding 20:: of the dynamoelectric machine 20 is deenergized and the voltage supplied to the train drive motor I8 is reduced to zero. From the foregoing it will be clear that this same operation could have been produced by movement of the pedals with the operator exerting only slight pressure on the pistol grip 40 thereby to cause the to act as a vernier to assist in aiming the gun.

The elevation operation is identical with the operation in train with the exception that it is initiated by vertical movement of the pistol grip. It may be desired to move the gun rapidly from its position bearing on one target to another position bearing on a new target. For this purpose a high speed switch is is mounted on the pistol grip 40. Depression of this high speed switch causes it to close its contacts and it will be noted that in closing its lower contacts, the RI drop compensating resistor 3| and a portion of the potentiometer 30 are excluded from the circuit of the control field winding 20a and the potentiometer 28. As a result, the dynamo-electric machine 20 must generate a higher voltage in order to bring about the balanced condition manual control target, the speed can 'be reduced to a very low value, whereas when large movements are required, a high speed of movement is obtainable.

Although in accordance with the provisions-oi the Patent Statutes this invention is described as embodied in concrete form and the principle thereof has been explained together with the best mode in which it is now contemplated applying that principle, it will be understood that the apparatusshown and described is merely iilustrative andthat the invention is not limited,

thereto, since alterations and modifications will readily suggest themselves to persons skilled inthe art, without departing from the true spirit of this invention or from the scope of the annexed claims.

What we-claim as new and desire to secure by I Letters Patent of the United States,ls

1. A turretcontrol systemcompr'ising, in combination-an electric motor for driving the turret, a dynamoelectric machine for supplying said motor, a master control switch and means controlled thereby for producing a control voltage. a potentiometer connected across the terminals of said dynamoelectric machine, a resistor connected in series relationship between said dynamoelectric machine and said motor, and a con-' trol field on said dynamoelectric machine responsive to the difference of said control voltage and the voltage drop across a portion of said potentiometer and resistor for controlling said dynamoelectric machine to supply a corresponding voltage to said motor. Y

2. A turret control system comprising, in combination, an electric motor for driving the turret, a dynamoelectrlc machine for supplying said motor, a master controlswitch and means controL ed thereby for producing a control voltage, a potentiometer connected across the terminals of said dynamoelectric machine, a resistor connected in series relationship between said dynamoelectric machine and said motor, a control field on said dynamoelectric machine responsive to the difference of said control voltage and the voltage drop across a portion of said potentiometer and resistor ior'controlling said dynamo electric machine to supply a corresponding voltage to said motonand a high speed switch tor connecting said control field winding to heresponsive to the diiierence 01 said control voltage and the voltage across a predetermined portion of said potentiometer.

3. A turret control system comprising in combination an electric motor for driving the turret. a dynamoelectric machine for supplying said motor, a master controller for said dynamo-electric machine comprising a manually movable member and a control potentiometer operated thereby for producing a control voltage, a second potentiometer connected across the output terminals or said dynamoelectric machine, and a control field winding on said dynamoelectric machine connected to be responsive to the difierence of said control voltage and the voltage across a selectable portion of said second potentiometer for controlling said dynamoelectric machine to supply a corresponding voltage to said motor, a second field winding on saiddynamoelectric machine, a switch on said master controller manually operable to one position to energize said control field winding and to deenergize said second field winding, and means biasing said switch to a second position to deenergize said control .field winding and connect said second field winding ior energization by the voltage of said machine in a direction opposite .to the magnetization of said control field winding.

'- 4. A turret control system comprising in com- 'bination an electric motor for driving the tur- -'ret;"'supply means iorsaid motor comprising a dynamoelectric machine provided witha control field winding and a second field winding connect- 'ed across the output terminals of said dynamoelectric machine for magnetization in a direction opposite to the magnetization of said control field winding, a master controller having a man- 'ually movable member anda control potentiom- "eter operated'therebyior producing a variable control voltage, a second potentiometer connect- --ed across .the output ofsaid dynamoelectric machine and connections from said potentiometers -to said control field winding for applying thereto a voltage proportional to the difleren'ce of said control voltage and the voltage across a selectable portion of said second potentiometer for con-' trolling. said dynamoelectric machine to supply a proportional voltage to said motor, and a hand grip switch on said master controllerhaving a member manually movable to'one position to en-' erglze said control fieldwindingand to disconnect said second control field winding from said output terminals and movable in response to release of manual pressure to deenergize said conntl'Ol field winding and to connect said second so field winding to said output terminals-thereby to eflect rapid reduction .01 the magnetization of said dynamoelectric machine to zero.

5. A turret control system comprising in combination an electric motor for driving the turret, supply means for said motor comprising a dynamoelectric machine provided with a control field winding, a source oi voltage and a control potentiometer connected across said source, a second potentiometer connected across the output terminals of said dynamoelectric machine, connections from said potentiometers to said control field winding for controlling said machine to supplya voltage to said motor proportional to the difference of the voltages derived from, said potentiometers, a foot operated member connected to said control potentiometer for eflecting coarse control of said motor, and a manually'operated .member connected to said control potentiometer 'i'or eflecting fine control of said motor.

6. A turret control system comprising in combination an electric motor for driving the turret, supply means ior said motor comprising a dynamoelectric machine providedwith a control field winding, a source of voltage and an adjustable, control potentiometer connected across said source providing a control voltage, a second potentiometer connected across the output terminals of said dynamoelectric machine, electrical connections from said potentiometers to said control field winding for controlling said dyna-. moelectricmachine to supply a voltage to said bination, a drive unit for driving the turret in train, a second drive unit for driving in elevation, a second drive unit for driving the turret in train, each of said units comprising an electric motor, supply means therefor comprising an armature reaction excited dynamoelectric machine provided with a control field winding, a device for producing a variable control voltage, a potentiometer connected across the output circuit of said dynamoelectric machine, and connections from said control voltage device and said potentiometer for applying to said iield control field winding a voltage proportional to the diflerence not said control voltage and the voltage across a predetermined portion of said potentiometer, a controller having a manually operated member movable in one direction to actuate one of said control voltage producing devices to eflect rotation of said turret in train and movable in another direction to actuate the other 0! said control voltage producing devices to effect operation in elevation, and a high speed switchon said .manual'ly operable memberior varying-said pre- 1 determinedv portion of said potentiometer.

MARTIN A. EDWARDS... KENNETH K. BOWMAN. 

